The mlmmj-receive binary is the one specified in the mailserver configuration file (aliases file), which
writes the mail to the <listdir>/incoming directory and invokes mlmmj-process unless the -P option is
specified. On systems using mailservers supporting the /etc/aliases file, a line to activate an mlmmj
managed mailinglist would look like this:
list: "|/usr/bin/mlmmj-receive -L /var/spool/mlmmj/list/"
It's very important to specify the full path to the binary, or the mailinglist will not function.
When the -F option is used, it will not fork in the background. The reason it forks is that if delivery
of a mail takes longer time than the mail server will allow a command to be idle before presumed dead,
the mail server would kill it.